Transistor parameters such as on-resistance and gate capacitance are subject to the effects of temperature, aging, and defect. However, manufacturing differences result in transistor performance that varies from one another. Because each of the transistor performs differently, parallel operation of transistors may not have identical conditions. Therefore, manufacturing differences make it difficult to control the performance of each transistor in a parallel system relative to one another.
Typical parallel operation requires forcing each of the transistors to carry an equal amount of current or, in other words, each transistor carries the same load. Traditionally this is considered the best means of balancing temperature across a system of parallel transistors in an attempt to have each transistor in the system wear at the same rate. But balancing current may result in relative overloading of some transistors that have higher on-resistances, as a result of manufacturing differences, and therefore higher temperatures relative to other transistors that have lower on-resistances. The transistors associated with the higher temperatures wear and age more quickly.
Vehicles such as aircraft may have one or more engines requiring the use of a motor with a motor controller to start each engine. The motor controller includes multiple parallel transistors. Traditionally, motor controllers for aircraft are designed and built to handle maximum requirements regardless of its eventual use. For example, similarly designed motor controllers could drive a 100 kilowatt (kW) motor or a 50 kW motor. Therefore, most motor controller are overbuilt and underutilized. It is desirable to have a lighter and more flexible motor controller with parallel outputs capable of driving various motors. For example, multiple controllers could be combined in parallel to provide a customized and correctly sized control system where different controllers could be tasked according to the needs of the vehicle.
It is with respect to these and other considerations that the disclosure herein is presented.